This invention relates to the novel configuration of a collapsible, or deployable, truss unit for combined use with a plurality or multiplicity of other similar units for the construction of desired frameworks. Typical applications of the truss units of this invention are medium to large scale structures in outer space such as huge antennas, solar power plants, space colonies, space plants and space stations. However, the possible applications of the truss units are not limited to such orbiting structures as the truss units obviously lend themselves to the construction of, for example, temporary or emergency structures on the earth as well.
All the building materials for the construction of orbiting structures in space must of course be transported from the earth as the payload of launch vehicles such as space shuttles. Any spacecraft imposes very stringent limitations on the volume and weight of its payload. Thus the building materials for space use must be as compact in size and light in weight as possible. Many space specialists agree that trusses represent the most promising building materials for the frameworks of medium to large size space constructions. Trusses are very light in weight in comparison with their size but, if not collapsible, are too bulky to be launched into space.
From the foregoing considerations, deployable truss structures are currently believed to be best suited for space constructions. Collapsed into compact form for launching, the deployable truss structures may be unfolded into required shape in space.
A well known example of unidirectionally deployable truss is the "single folding mast" disclosed in "Development of Deployable Structures for Large Space Platform Systems", NASA CR-17093. Such unidirectionally deployable trusses find extensive applications to the keel beams of space stations, the booms of large space antennas, etc. Like many other deployable structures of this class, the "single folding mast" structure is collapsed by bending some of its constituent members at the joints at their midpoints and by telescoping other members.
Such conventional construction is objectionable because its constituent members do not have sufficient mechanical strength at their midportions, which are most closely associated with Euler buckling, resulting in the insufficient rigidity of the complete structure. It might be contemplated to employ very powerful, sturdy mechanisms for locking the joints when the structure is deployed, in order to enhance the rigidity of the deployed structure. However, such locking mechanisms would add considerably to the weight of the structure.
It is desirable that any deployable truss structure be unfolded automatically or at least semiautomatically in outer space. This objective demands utmost reliability in the various working parts and mechanisms of the structure. The joint locks should be not only reliable in operation but also as small in number as possible. The "single folding mast" structure requires, typically, eight locks per unit. This number is not so small as can be desired.